The printing industry uses sleeves as a carrier for mounting printing plates on the print cylinder so that the printing plate is not mounted directly on the cylinder. This results in the advantage that one can leave the printing plates mounted to the less expensive sleeve rather than requiring unmounting the plates from the base print cylinder or having to tie up an expensive print cylinder while an idle job remains mounted. Frequently the same printing plate will be used in the near future and thus using the sleeve will save on set up time.
Various approaches have been taken in the art to provide carrier sleeves for such printing cylinders. Reference is made to U.S. Pat. Nos. 3,978,254, 4,030,415, 4,601,928, 4,903,597, 5,215,013, 5,256,459, 5,301,610, 5,425,693 and 5,458,708 which exemplify known approaches. All of the details of these patents are incorporated herein by reference thereto.
A general approach taken in the prior art is to use an expandable sleeve which would be initially of an inside diameter no greater than and preferably smaller than the outside diameter of the cylinder. The cylinder includes structure for causing the sleeve to expand so that the sleeve can then be assembled onto the cylinder in a sliding movement. A concern with this approach is that if the sleeve too readily expands, plate buckling might occur.
An object of this invention is to provide an improved printing cylinder sleeve assembly which overcomes disadvantages of the prior art approaches.
A further object of this assembly is to provide such a printing cylinder sleeve assembly wherein structure is incorporated to restrict the degree of expansion.
A still further object of this invention is to provide such a printing cylinder assembly which would be economical to make without sacrifice to the ease of mounting the sleeve on the cylinder.
In accordance with this invention the sleeve is in the form of a multi-layer laminate wherein the inner and outer layers are of a readily expandable material, such as the types of materials used in the prior art. The laminate includes at least one intermediate layer which is less expandable in its characteristics, having greater stiffness, so as to restrict the total expansion of the laminate sleeve assembly.
In a preferred practice of this invention the intermediate layer is made of conventional paper such as kraft paper or newsprint, impregnated paper, pulp/paper products, scrim, very thin fiberglass fabric, aluminum sheets and/or other suitable non-woven material. The expansion restricting layer is preferably continuous by being a non-perforated sheet. Alternatively the sheet could have holes or openings. The layer may also be discontinuous by being in the form of individual spaced strands or strips located between the inner and outer layers. Where plural expansion restricting layers are used, the individual layers may be of the same or of different structure than each other.